This invention is an improvement over my improved bearing isolator described and claimed in U.S. patent application Ser. No. 08/701,815 filed Aug. 21, 1996.
Oil mist lubrication has been widely used in the Hydrocarbon Processing and Primary Metal industries as a means of delivering a constant supply of fresh lubricant directly to the bearings of various types in order to enhance the reliability of the rotating equipment.
Oil mist systems continuously provide a fresh supply of oil film to the bearings, pressurize the bearing housing against outside contaminants and cool the bearings slightly. A mist generator in which petroleum or synthetic lubricant is made into a fine aerosol mist of droplets, measuring 3-5 microns in size, is mixed with carrier air. The mixture is delivered by means of pipes, conduits, and tubings and is delivered automatically under low pressure to the bearing area. A volume of air is continuously exhausted into the workplace area and the air contains oil mist, creating a back pressure in the bearing housing equal to the exit losses incurred. The disadvantage of this oil mist lubrication system is the constant escape of air/oil mist. This is often termed "stray mist" which permeates the entire area around and on the misted equipment.
This stray mist or oil accumulation in the air has been taken care of in an environmental sense by proper ventilation and use of good mistable lubricants to reduce the amount of stray mist to a low level. However, there is always a significant amount of stray oil mist that escapes and is deposited on the surfaces in the workplace despite the best ventilation systems.
Government agencies, namely the Environmental Protection Agency (EPA), has tolerated the mist in the environment because it has not been proven to be harmful when ingested into the human body through inhalation, ingestion, or skin absorption. The most common way is inhalation and the National Institute of Occupation Safety and Health in the United States has established a threshold limit of oil mist in the air as 5 mg. per cubic meter. However, concentrations greater than 0.4 mg. per cubic meter result in a visible haze or cloud of mist, which accumulates on the equipment and surrounding structures, especially the floor, which renders this equipment slippery and unsafe in many ways. In any event, this oil must be cleaned-up and the oily residue disposed of in an environmentally safe manner which requires a great deal of time and money.
This constant loss of oil and the requirements of cleaning it up necessitated a method of providing the advantages of oil mist lubrication without the disadvantages, i.e., loss of oil through the stray mist emitted into the surrounding environment.
Applicant's invention will implement the retention of vapor in a housing. This implementation would remove any visible emission, such as fog, steam, mist, etc., or would be operable with a gas at a temperature below its critical temperature and/or for retention in the housing of the combination of a vaporized substance and air or other carriers. In many instances, such control is needed, such as to prevent steam from entering into a housing containing oil or a substance, such as oil in vapor form.
Applicant's invention has been found to provide absolute control over oil mist escaping into the atmosphere along with the air carrier.
The seal effective for use in containing stray mist or vapors as described in my prior patent application had certain disadvantages, which this present invention overcomes. The prior invention was difficult to install because of the unforgiving nature of the coalescing ring. The ring made of lubricous material, designed to coalesce the liquid did not readily conform to the groove and the outside diameter of the shaft.
The coalescing member also tended, because of its intimate contact with the rotating shaft, to present a possibility of grooving the shaft. Any such grooving would permit leakage of lubricant past the coalescing ring, thereby placing an additional sealing burden on the remaining portion of the seal.
The improved seal of the present invention overcomes any concern of grooving of the shaft by relocating the coalescing ring into the vertical plane in a groove between the stator and a second rotor.
This invention, thus, includes a second rotor, but provides for better coalescence, is easier to assemble and adds centrifugal forces to improve coalescence.